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Results for “MYB46”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Mitogen-activated protein kinase 6 negatively regulates secondary wall biosynthesis by modulating MYB46 protein stability in Arabidopsis thaliana

The R2R3-MYB transcription factor MYB46 functions as a master switch for secondary cell wall biosynthesis, ensuring the exquisite expression of the secondary wall biosynthetic genes in the tissues where secondary walls are critical for growth and development. At the same time, suppression of its function is needed when/where formation of secondary walls is not desirable. Little is known about how this opposing control of secondary cell wall formation is achieved. We used both transient and transgenic expression of MYB46 and mitogen-activated protein kinase 6 (MPK6) to investigate the molecular mechanism of the post-translational regulation of MYB46. We show that MYB46 is phosphorylated by MPK6, leading to site specific phosphorylation-dependent degradation of MYB46 by the ubiquitin-mediated proteasome pathway. In addition, the MPK6-mediated MYB46 phosphorylation was found to regulate in planta secondary wall forming function of MYB46. Furthermore, we provide experimental evidences that MYB83, a paralog of MYB46, is not regulated by MPK6. The coupling of MPK signaling to MYB46 function provides insights into the tissue- and/or condition-specific activity of MYB46 for secondary wall biosynthesis.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Jasmonate activates secondary cell wall biosynthesis through MYC2–MYB46 module

Formation of secondary cell wall (SCW) is tightly regulated spatiotemporally by various developmental and environmental signals. Successful fine-tuning of the trade-off between SCW biosynthesis and stress responses requires a better understanding of how plant growth is regulated under environmental stress conditions. However, the current understanding of the interplay between environmental signaling and SCW formation is limited. The lipid-derived plant hormone jasmonate (JA) and its derivatives are important signaling components involved in various physiological processes including plant growth, development, and abiotic/biotic stress responses. Recent studies suggest that JA is involved in SCW formation but the signaling pathway has not been studied for how JA regulates SCW formation. We tested this hypothesis using the transcription factor MYB46, a master switch for SCW biosynthesis, and JA treatments. Both the transcript and protein levels of MYB46, a master switch for SCW formation, were significantly increased by JA treatment, resulting in the upregulation of SCW biosynthesis. We then show that this JA-induced upregulation of MYB46 is mediated by MYC2, a central regulator of JA signaling, which binds to the promoter of MYB46. We conclude that this MYC2-MYB46 module is a key component of the plant response to JA in SCW formation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

XND1 Regulates Secondary Wall Deposition in Xylem Vessels through the Inhibition of VND Functions

Secondary wall deposition in xylem vessels is activated by Vascular-Related NAC Domain proteins (VNDs) that belong to a group of secondary wall NAC (SWN) transcription factors. By contrast, Xylem NAC Domain1 (XND1) negatively regulates secondary wall deposition in xylem vessels when overexpressed. The mechanism by which XND1 exerts its functions remains elusive. We employed the promoter of the fiber-specific Secondary Wall-Associated NAC Domain1 (SND1) gene to ectopically express XND1 in fiber cells to investigate its mechanism of action on secondary wall deposition. Ectopic expression of XND1 in fiber cells severely diminished their secondary wall deposition and drastically reduced the expression of SWN-regulated downstream transcription factors and secondary wall biosynthetic genes but not that of the SWN genes themselves. Transactivation analyses revealed that XND1 specifically inhibited SWN-activated expression of these downstream genes but not their MYB46-activated expression. Both the NAC domain and the C-terminus of XND1 were required for its inhibitory function and its NAC domain interacted with the DNA-binding domains of SWNs. XND1 was shown to be localized in the cytoplasm and the nucleus and its co-expression with VND6 resulted in the cytoplasmic sequestration of VND6. Furthermore, the C-terminus of XND1 was indispensable for the XND1-mediated cytoplasmic retention of VND6 and its fusion to VND6 was able to direct VND6 to the cytoplasm and render it unable to activate the gene expression. Since the XND1 gene is specifically expressed in xylem cells, these results indicate that XND1 acts through inhibiting VND functions to negatively regulate secondary wall deposition in xylem vessels.

Cell Biology↗
DOE OSTI2021

Field evaluation of transgenic hybrid poplars with desirable wood properties and enhanced growth for biofuel production by bicistronic expression of PdGA20ox1 and PtrMYB3 in wood-forming tissue

Background: To create an ideotype woody bioenergy crop with desirable growth and biomass properties, we utilized the viral 2A-meidated bicistronic expression strategy to express both PtrMYB3 ( MYB46 ortholog of Populus trichocarpa , a master regulator of secondary wall biosynthesis) and PdGA20ox1 (a GA20-oxidase from Pinus densiflora that produces gibberellins) in wood-forming tissue (i.e., developing xylem). Results: Transgenic Arabidopsis plants expressing the gene construct DX15::PdGA20ox1-2A-PtrMYB3 showed a significant increase in both stem fresh weight (threefold) and secondary wall thickening (1.27-fold) relative to wild-type (WT) plants. Transgenic poplars harboring the same gene construct grown in a greenhouse for 60 days had a stem fresh weight up to 2.6-fold greater than that of WT plants. In a living modified organism (LMO) field test conducted for 3 months of active growing season, the stem height and diameter growth of the transgenic poplars were 1.7- and 1.6-fold higher than those of WT plants, respectively, with minimal adverse growth defects. Although no significant changes in secondary wall thickening of the stem tissue of the transgenic poplars were observed, cellulose content was increased up to 14.4 wt% compared to WT, resulting in improved saccharification efficiency of the transgenic poplars. Moreover, enhanced woody biomass production by the transgenic poplars was further validated by re-planting in the same LMO field for additional two growing seasons. Conclusions: Taken together, these results show considerably enhanced wood formation of our transgenic poplars, with improved wood quality for biofuel production.

09 BIOMASS FUELS↗